Welboren Willem-Jan, van Driel Marc A, Janssen-Megens Eva M, van Heeringen Simon J, Sweep Fred Cgj, Span Paul N, Stunnenberg Hendrik G
Department of Molecular Biology, Faculty of Science, Nijmegen Centre for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands.
EMBO J. 2009 May 20;28(10):1418-28. doi: 10.1038/emboj.2009.88. Epub 2009 Apr 4.
We used ChIP-Seq to map ERalpha-binding sites and to profile changes in RNA polymerase II (RNAPII) occupancy in MCF-7 cells in response to estradiol (E2), tamoxifen or fulvestrant. We identify 10 205 high confidence ERalpha-binding sites in response to E2 of which 68% contain an estrogen response element (ERE) and only 7% contain a FOXA1 motif. Remarkably, 596 genes change significantly in RNAPII occupancy (59% up and 41% down) already after 1 h of E2 exposure. Although promoter proximal enrichment of RNAPII (PPEP) occurs frequently in MCF-7 cells (17%), it is only observed on a minority of E2-regulated genes (4%). Tamoxifen and fulvestrant partially reduce ERalpha DNA binding and prevent RNAPII loading on the promoter and coding body on E2-upregulated genes. Both ligands act differently on E2-downregulated genes: tamoxifen acts as an agonist thus downregulating these genes, whereas fulvestrant antagonizes E2-induced repression and often increases RNAPII occupancy. Furthermore, our data identify genes preferentially regulated by tamoxifen but not by E2 or fulvestrant. Thus (partial) antagonist loaded ERalpha acts mechanistically different on E2-activated and E2-repressed genes.
我们使用染色质免疫沉淀测序（ChIP-Seq）来绘制雌激素受体α（ERα）结合位点图谱，并分析在雌激素（E2）、他莫昔芬或氟维司群作用下，MCF-7细胞中RNA聚合酶II（RNAPII）占据情况的变化。我们鉴定出10205个对E2有高置信度的ERα结合位点，其中68%含有雌激素反应元件（ERE），只有7%含有叉头框蛋白A1（FOXA1）基序。值得注意的是，在E2暴露1小时后，已有596个基因的RNAPII占据情况发生显著变化（59%上调，41%下调）。虽然RNAPII启动子近端富集（PPEP）在MCF-7细胞中频繁出现（17%），但仅在少数E2调控基因上观察到（4%）。他莫昔芬和氟维司群部分降低ERα与DNA的结合，并阻止RNAPII在E2上调基因的启动子和编码区加载。两种配体对E2下调基因的作用不同：他莫昔芬作为激动剂下调这些基因，而氟维司群拮抗E2诱导的抑制作用，且常常增加RNAPII占据情况。此外，我们的数据鉴定出优先受他莫昔芬调控而非E2或氟维司群调控的基因。因此（部分）拮抗剂负载的ERα对E2激活基因和E2抑制基因的作用机制不同。
